Does the reset button help?

h-a-l-9000 wrote:

Does the reset button help?

Thanks, yes this does help. 😀 After I exit the BIOS and the mobo has "frozen", I momentarily short the Reset jumper pins with a screwdriver, and then the mobo boots up again, with the BIOS POST messages appearing on the screen...

Take care with that, I once slipped when using a screwdriver to short the power button pins on an ATX board. The sparks seemed to kill a few things. 🤣

ratfink wrote:

Take care with that, I once slipped when using a screwdriver to short the power button pins on an ATX board. The sparks seemed to kill a few things. 🤣

🤣
I've been very careful up to now. No sparks, yet. No spilt coffee either! 😀

Maybe a BIOS update would help (if the BIOS hangs BEFORE the reset).

Does it happen only when the BIOS resets the board? Does it happen when you reboot from the OS? "Soft reboots" (as CTRL+ALT+DEL in DOS prompt) locks the motherboard or it happens only when a "hard reset" is done? Does it happen when you use the reset button?

Zup wrote:

Maybe a BIOS update would help (if the BIOS hangs BEFORE the reset).

Does it happen only when the BIOS resets the board? Does it happen when you reboot from the OS? "Soft reboots" (as CTRL+ALT+DEL in DOS prompt) locks the motherboard or it happens only when a "hard reset" is done? Does it happen when you use the reset button?

Hello. 😀 Here are my answers to your questions -

The BIOS does not hang while I am using the BIOS setup area, and therefore, it does not hang before any reset.
The mobo always hangs when I exit the BIOS, whether any changes have been made or not.
The mobo always hangs when I CTRL+ALT+DEL at a DOS prompt.

When the mobo has frozen in this manner, I can "wake the mobo up again" by shorting the 2 Reset Pins on the mobo. (Whatever changes were made and saved inside the BIOS setup area appear to be successfully saved, which is good news.)

When I switch on power to the mobo for the first time, I get no problems at all - DOS boots up correctly.

Please note: unfortunately, ATM, I cannot test whether an operating system such as Win95/Win98 causes any problems when this operating system resets the system, as I did not install Win95/98 on this machine at the time when I tested it.

Thanks a lot.

One of those diagnostic POST code cards might be useful here... (I wonder where you keep getting all the broken crap)

All the other components work with other mainboards, right?

h-a-l-9000 wrote:

One of those diagnostic POST code cards might be useful here... (I wonder where you keep getting all the broken crap)

All the other components work with other mainboards, right?

Yes, I remember looking at one of those items on ebay about a month ago, and thinking it could be useful for something. Perhaps now is the time to get one?! I typed in this search string in to ebay -

diagnostic post

= 151 results. (Any buying advice would be most welcome, as I've never used one of these things before.)

The components used in this mobo were very simple: 1 stick of RAM (which I have used in 2 other boards), and 1 PCI graphics card (which I have used in many other boards). I have also re-used the CPU in another mobo, and it seems to work OK.

Thanks. 😀

And the one you forgot? 😀

h-a-l-9000 wrote:

And the one you forgot? 😀

Hehe, you got me peering over one of my 486 boards here, making me think "what I have I forgotten to mention..."

Here are the other items plugged in to my typical 486 mobo testing set up -

* Keyboard (5 pin)
* RS232 com/serial port cable <- could be a problem here perhaps?! (This is used for a serial mouse - but the cable used may not be the exact cable intended for the mobo.)
* Cache chips, all untested
* Floppy disk cable
* IDE HDD cable
* Power cable, with an ATX to AT power converter gadget attached to it, which leads to a Nexus ATX power supply.
* Please note: there was no jumper over the set of 3 turbo switch pins.

I hope I haven't forgotten anything! 😀

About the POST card: I guess you'd want one with PCI and ISA slot combined so you can use it on modern systems too...
Then these cards have, depending on the price, additional useful/useless features.

Different sound by code... expendable IMO.

LEDs signalling the presence of the different power lines... might be useful for you with your -5V trouble 😉 but the correctness of the voltage level is probably not checked - indicator means "there is something there".

Display from both sides of the card... it's your decision wether you need it

Those with the parallel port connector on it are for notebooks.

Previous codes by pushing a button... might be useful

Hehe, you got me peering over one of my 486 boards here, making me think "what I have I forgotten to mention..."

I was thinking about the power supply 😀

h-a-l-9000 wrote:

Hehe, you got me peering over one of my 486 boards here, making me think "what I have I forgotten to mention..."

I was thinking about the power supply 😀

Yes of course. It's a Nexus 350W ATX PSU with a -5v rail. It's possible that the ATX to AT power cable converter gadget may not be functioning correctly.

I think it's essential for me to test whether this ATX to AT power converter gadget is working properly. I need to ensure that the -5v power is being correctly delivered from the PSU to the mobo. In order to determine this, do I need something called a multimeter?

Wikipedia has this page on multimeters -

http://en.wikipedia.org/wiki/Multimeter

Thanks a lot! 😁

Missing -5V doesn't cause this kind of problem. And there is not that much that can be wrong about the AT/ATX adapter...

A Multimeter is always useful to have though.